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Smart fabric heats up under the sun

uwaterloo.ca

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Re: Smart fabric heats up under the sun

#31

Post by eqvinox »

After the recent "save 30% power in datacenters" thing¹, I've grown a bit weary of the university of waterloo, and "things get warm in the sun"² isn't helping.

¹ it was a IRQ polling change in the Linux kernel that only helps network-heavy applications under high load with good NIC offload capabilities. I'll accept it might save 30% in the "best degenerate" case, but it'll be nowhere close in general. https://news.ycombinator.com/item?id=42841981

² yes I'm exaggerating. The problem is I have no clue about this heat thing, but I do have an understanding Linux NAPI/IRQ behavior, and that made me with good reason call massive exaggeration there. So what am I to do when I see something from this same source that I don't know about?

Re: Smart fabric heats up under the sun

#32

Post by viraptor »

hammock wrote: post #29
viraptor wrote: post #17

> Notably, when exposed to 600 W m−2 irradiation for 600 s, the equilibrium temperature of the photo-thermochromic elastic fiber rises impressively from the ambient 20.0 °C to 53.5 °C. Does anyone know what's the expected raise from that much energy in basic cotton for comparison?

If we assume a clothes dryer is 3000W, how long does it take a cotton shirt to get heated from 20c to 53c? A few minutes? So perhaps this fabric heats up 3-5x faster

Different kind of heat transfer. Clothes in the dryer match the temperature of the heated air around them. This paper is about radiated heat captured by the cloth.

Re: Smart fabric heats up under the sun

#33

Post by hammock »

viraptor wrote: post #32
hammock wrote: post #29

Earlier quoted context omitted.

If we assume a clothes dryer is 3000W, how long does it take a cotton shirt to get heated from 20c to 53c? A few minutes? So perhaps this fabric heats up 3-5x faster

Different kind of heat transfer. Clothes in the dryer match the temperature of the heated air around them. This paper is about radiated heat captured by the cloth.

Ok stick your shirtsleeve in a toaster. 1000W? How many minutes until it’s 125F. Same answer?

Re: Smart fabric heats up under the sun

#34

Post by viraptor »

hammock wrote: post #33
viraptor wrote: post #32

Earlier quoted context omitted.

Different kind of heat transfer. Clothes in the dryer match the temperature of the heated air around them. This paper is about radiated heat captured by the cloth.

Ok stick your shirtsleeve in a toaster. 1000W? How many minutes until it’s 125F. Same answer?

If I understand the quote from the paper, it's not quite the same. They're putting a controlled amount of irritation over a long time on the cloth. It seems like the change is a higher temperature than other fabrics, not necessarily faster (maybe, but not noted)

Re: Smart fabric heats up under the sun

#35

Post by foolswisdom »

eqvinox wrote: post #31

After the recent "save 30% power in datacenters" thing¹, I've grown a bit weary of the university of waterloo, and "things get warm in the sun"² isn't helping. ¹ it was a IRQ polling change in the Linux kernel that only helps network-heavy applications under high load with good NIC offload capabilities. I'll accept it might save 30% in the "best degenerate" case, but it'll be nowhere close in general. https://news.yc…

> So what am I to do when I see something from this same source that I don't know about?

Well there's always https://en.m.wikipedia.org/wiki/Gell-Mann_amnesia_effect>. Sounds like your not as vulnerable though.

Re: Smart fabric heats up under the sun

#38

Post by DangitBobby »

10000truths wrote: post #25
wongarsu wrote: post #22

Earlier quoted context omitted.

That depends on what you believe was there the instant before the universe was created. Answering that with "nothing" would indeed violate all kinds of conservation laws. The currently most popular theory is that time and space also started at the big bang. If that's true there is no "before the big bang", and thus the energy was always there. Other possible answers: - the energy was there but kind of dormant, then s…

Or, you know, an higher and/or omnipotent entity. At some point along the causal chain, there is no "testing" - you are forced to resort to metaphysical reasoning.

This doesn't actually solve the original problem. Either something was always there or something can come from nothing, and both of those seem to violate causality as we understand it. Saying "God was always there" isn't really that different from "The universe was always there" when it comes to resolving the violation of causality.

Re: Smart fabric heats up under the sun

#39

Post by koakuma-chan »

DangitBobby wrote: post #38
10000truths wrote: post #25

Earlier quoted context omitted.

Or, you know, an higher and/or omnipotent entity. At some point along the causal chain, there is no "testing" - you are forced to resort to metaphysical reasoning.

This doesn't actually solve the original problem. Either something was always there or something can come from nothing, and both of those seem to violate causality as we understand it. Saying "God was always there" isn't really that different from "The universe was always there" when it comes to resolving the violation of causality.

Obviously, something was always there. "Always" refers to the run time of our simulation.

Re: Smart fabric heats up under the sun

#40

Post by 10000truths »

DangitBobby wrote: post #38
10000truths wrote: post #25

Earlier quoted context omitted.

Or, you know, an higher and/or omnipotent entity. At some point along the causal chain, there is no "testing" - you are forced to resort to metaphysical reasoning.

This doesn't actually solve the original problem. Either something was always there or something can come from nothing, and both of those seem to violate causality as we understand it. Saying "God was always there" isn't really that different from "The universe was always there" when it comes to resolving the violation of causality.

An omnipotent being would presumably have invented causality and time, and therefore not be bound by the axioms thereof.
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